WO2021004196A1 - 射频热消融***及其控制方法 - Google Patents
射频热消融***及其控制方法 Download PDFInfo
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- WO2021004196A1 WO2021004196A1 PCT/CN2020/093767 CN2020093767W WO2021004196A1 WO 2021004196 A1 WO2021004196 A1 WO 2021004196A1 CN 2020093767 W CN2020093767 W CN 2020093767W WO 2021004196 A1 WO2021004196 A1 WO 2021004196A1
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- A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
- A61B18/08—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by means of electrically-heated probes
- A61B18/082—Probes or electrodes therefor
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- A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
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- A61B18/08—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by means of electrically-heated probes
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- A61B2017/00017—Electrical control of surgical instruments
- A61B2017/00115—Electrical control of surgical instruments with audible or visual output
- A61B2017/00119—Electrical control of surgical instruments with audible or visual output alarm; indicating an abnormal situation
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- A61B2018/00571—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for achieving a particular surgical effect
- A61B2018/00577—Ablation
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- A61B90/06—Measuring instruments not otherwise provided for
- A61B2090/064—Measuring instruments not otherwise provided for for measuring force, pressure or mechanical tension
- A61B2090/065—Measuring instruments not otherwise provided for for measuring force, pressure or mechanical tension for measuring contact or contact pressure
Definitions
- This application relates to ablation technology, in particular to radio frequency thermal ablation technology.
- Radiofrequency ablation technology is a modern minimally invasive technology that is widely used. In recent years, radiofrequency ablation has been applied to a variety of lesions such as the heart, cancer tumors, and even skin. Radio frequency thermal ablation technology is that radio frequency energy does not directly enter the human body, but generates heat energy inside the device, and then transfers the heat energy to the human body to produce a thermal ablation effect. Because this technology has less trauma to the human body and the ablation method can be precisely controlled by an electronic system, it has become a technology that is more commonly used in modern active minimally invasive surgery.
- radiofrequency ablation probes are currently used to ablate bronchial nerves to treat asthma, ablate prostate tissue through the urethra to treat enlarged prostate, ablate peripheral blood vessels to shrink them, ablate esophageal surface tissue to treat esophageal cancer, ablate uterine surface tissue to treat uterine cancer, etc. .
- These organs of the human body such as blood vessels, bronchi, urethra, esophagus, uterus, etc., are basically slender and tubular structures, and have similarities in the appearance, function and performance of the RF probe.
- Radio frequency thermal ablation probes mostly use closed and externally insulated resistive heating elements, such as patents US7837677, EP1906853, US2017/0202600A1, EP2662044, US10357305, etc.
- the characteristic is that the winding does not form a current loop with human tissue, so the common practice in this field is to ignore the external
- the effect of tissue on the characteristics of resistive windings is treated only by simple temperature feedback control.
- the area heated by thermal ablation is generally not just a point, but an area.
- the most typical situation is when the organ wall is tightly attached to the surface of the heating winding due to accidental high temperature when the sensing means are insufficient, the treatment continues due to the lack of effective sensing means, resulting in stickiness and even carbonization, and even medical accidents.
- the purpose of this application is to provide a radio frequency thermal ablation system and its control method, which can use the parasitic capacitance between turns of the closed winding to monitor the state of the aperture shrinkage of the tubular organ during the thermal ablation process, and then configure the monitoring by designing the winding sensitivity Working point, enhance the sensitivity to the parasitic capacitance between the circles, thereby effectively controlling the treatment process, making the key treatment parameters such as the distance of the organ tube wall controllable in the thermal ablation treatment process, safer and more accurate ablation depth control.
- This application discloses a radio frequency thermal ablation system, including:
- thermo ablation probe includes an insulated heating winding with an inductance characteristic, the inductance characteristic is used to configure the frequency operating point during detection, and enhance the sensitivity of detecting parasitic capacitance between winding turns;
- a radio frequency generator for outputting radio frequency power for heating to the heating winding
- a device for monitoring the parasitic capacitance between the windings is used to monitor the change of the parasitic capacitance between the insulation heating windings caused by the tubular organ wall approaching the insulation heating winding and/or the solidification of body fluid during the heating process;
- the control device is used to control the amount of radio frequency power output by the radio frequency generator to the heating winding according to the change of the parasitic capacitance between the turns detected by the parasitic capacitance monitoring device.
- the parasitic capacitance monitoring device between the windings monitors the change of the parasitic capacitance between the heating windings by detecting the vector voltage and current of the heating winding.
- control device is also used to calculate the parasitic capacitance between the heating windings based on the vector voltage and current of the heating winding detected by the parasitic capacitance monitoring device between the windings, and extract the heating The impedance phase after the combination of the parasitic capacitance between the winding turns and the winding inductance characteristics, if the phase enters a preset interval, the radio frequency transmitter is controlled to stop outputting radio frequency power to the heating winding.
- the output frequency of the control device is continuously adjustable; the control device is also used to search and adjust the working frequency of the radio frequency power output by the radio frequency generator in a preset working frequency range, so that The difference between the working frequency and the resonance frequency of the complex impedance is less than a predetermined threshold.
- the operating frequency range covers the range of the phase of the complex impedance of the heating winding from 90 degrees to -90 degrees.
- the inter-turn spacing of the heating winding satisfies the following condition: the resonance frequency corresponding to the combination of the inductance of the heating winding and the expected parasitic capacitance between the turns is within the operating frequency range, wherein the expected turn
- the inter-turn parasitic capacitance is the inter-turn parasitic capacitance of the heating winding when the distance between the blood vessel tissue and the thermal ablation probe is within a predetermined range.
- it further includes a memory for storing the pre-calibrated resonance frequency, which is used as the target resonance frequency for reading by the control device.
- the application also discloses a control method of a radio frequency thermal ablation system.
- the radio frequency thermal ablation system includes: a thermal ablation probe, the thermal ablation probe includes an insulated heating winding with inductance characteristics, and the inductance characteristics are used to configure the frequency of detection The working point is to enhance the sensitivity of detecting the parasitic capacitance between the winding turns; the radio frequency generator is used to output the radio frequency power for heating to the insulating heating winding; the method includes:
- the radio frequency generator outputs radio frequency power for heating to the insulating heating winding
- the radio frequency power output from the radio frequency generator to the insulation heating winding is controlled.
- the monitoring the change of the parasitic capacitance between the insulation heating winding turns during the heating process further includes:
- the controlling the amount of radio frequency power output from the radio frequency generator to the heating winding according to the change of the parasitic capacitance between the turns detected by the parasitic capacitance monitoring device further includes:
- the radio frequency transmitter is controlled to stop outputting radio frequency power to the heating winding.
- the method further includes:
- an insulated heating winding with inductance is designed for the thermal ablation probe.
- the insulated heating winding with inductance characteristics adopts a centralized winding method, so that the inductance distribution of the insulated heating winding is more concentrated, and can be concentrated and targeted for sensing and heating.
- the tube wall of the tubular organ being thermally ablated, the solidified body fluid and the inductive part of the insulating heating winding will form a parasitic capacitance between the loops, and as the tubular organ shrinks and the degree of liquid coagulation deepens, the The parasitic capacitance between the turns gradually increases.
- the parasitic capacitance between the turns and the inductance of the insulation heating winding approach resonance, and the phase change of the overall complex impedance with respect to the rate of change of the frequency gradually increases, so the overall complex impedance is detected
- the sensitivity of the phase is improved, which in turn increases the sensitivity of the parasitic capacitance between turns based on the phase of the complex impedance.
- the real-time detection capability of the parasitic capacitance between the turns during the thermal ablation process can be improved. Therefore, monitoring the change of the complex impedance of the inductive insulating heating winding during the thermal ablation treatment can more accurately monitor and control the parasitic capacitance between the circles, and then more accurately calculate and control the degree of the organ wall approaching the thermal ablation probe and the condensation of surrounding body fluids. Degree.
- the thermal ablation treatment process can be controlled and optimized in real time according to the monitoring results. For example, when the complex impedance is close to the preset value, it is judged that the tubular organ wall atrophy is close to the ablation probe.
- the control device can reduce the power output and reduce the tube. The shrinkage rate of the wall, so as to more smoothly and accurately control the treatment effect.
- the sensing circuit has better sensitivity to phase detection near the phase of 0, in the embodiment of the present application, in the preset operating frequency range, search and adjust the output of the RF power of the RF generator Working frequency, so that the difference between the working frequency and the resonance frequency of the complex impedance is less than a predetermined threshold; further by setting the inter-turn spacing of the insulation heating winding, the inductance of the insulation heating winding and the expected parasitic capacitance between the turns correspond to the combination
- the resonance frequency is within the working frequency range, where the expected inter-loop parasitic capacitance is the inter-loop parasitic capacitance of the insulating heating winding when the distance between the blood vessel tissue and the thermal ablation probe is within a predetermined range, thereby improving the sensitivity of monitoring and control, Make the final thermal ablation treatment effect better.
- Fig. 1 is a schematic structural diagram of a radio frequency thermal ablation system according to the first embodiment of the present application
- Fig. 2 is an overall schematic diagram of an exemplary radio frequency ablation probe according to the first embodiment of the present application
- FIG. 3 is a schematic diagram of a winding method of an insulated heating winding according to an embodiment of the first embodiment of the present application
- Example A is a schematic diagram of a distal end cross-sectional view of an exemplary radio frequency ablation probe in Example A according to the first embodiment of the present application;
- Example 5 is a schematic diagram of the inner wall of the tubular organ close to the surface of the example radiofrequency ablation probe during thermal ablation in Example A of the first embodiment of the present application;
- Example 6 is a schematic diagram of the parasitic capacitance formed between the insulating heating winding and the inner wall of the tubular organ in Example A according to the first embodiment of the present application;
- FIG. 7 is a schematic diagram of the complex impedance change trend of the insulating heating winding caused by the change of the parasitic capacitance between the coils during the thermal ablation treatment in Example A of the first embodiment of the present application;
- FIG. 8 is a schematic diagram of a low-frequency sampling method of voltage and current of the insulating heating winding in Example A according to the first embodiment of the present application;
- Example 9 is a schematic diagram of the impedance characteristics near the resonance point of the inductance and inter-turn parasitic capacitance of the insulating heating winding in Example A according to the first embodiment of the present application;
- FIG. 10 is a schematic structural diagram of a radio frequency thermal ablation system with an exemplary radio frequency generator circuit block diagram according to the first embodiment of the present application;
- FIG. 11 is a schematic diagram of a circuit parasitic capacitance calibration mechanism according to the first embodiment of the present application.
- FIG. 12 is a schematic flowchart of a control method of a radio frequency thermal ablation system according to the second embodiment of the present application.
- FIG. 13 is a schematic diagram of the calibration process flow of the resonance frequency according to the present application.
- Fig. 14(A) is a process of using the calibrated and stored tubular organ of each probe to fit the target resonance frequency fr as the target output frequency of the radio frequency generator to control the entire treatment process in the case of the thermal ablation probe with memory according to the present application
- Fig. 14(B) is a schematic flow diagram of the thermal ablation probe of the present application without a memory using a unified nominal frequency as the target output frequency of the radio frequency generator to control the entire treatment process.
- Ablation Applying energy or substances to degenerate body organs to achieve therapeutic effects.
- Thermal ablation an ablation technique that applies thermal energy.
- Radio frequency transmitter An electronic instrument that can generate and control high-frequency signals. It can be used with ablation probes in ablation applications to send radio frequency energy to the ablation probe to achieve ablation treatment effects.
- Swelling anesthesia Inject anesthetic fluid into the patient's body to form swelling and compression while forming anesthesia to the organs to achieve auxiliary effects during blood vessel ablation.
- EEPROM Electrically Erasable Programmable read only memory, programmable read-only memory that can be erased when charged.
- vascular thermal ablation technology generally relies on adjusting the heating time at a certain temperature to control the degree of vasoconstriction. Therefore, the treatment devices currently on the market generally control two parameters: heating temperature and heating time. The two are indirectly related to the parameters that need to be controlled during treatment, such as the degree of tube wall contraction or the degree of body fluid coagulation. Simply put, the longer the heating time, the higher the degree of vasoconstriction. However, because of the different shapes and sizes of organs, heating time and temperature cannot uniquely determine the degree of organ wall contraction or the degree of body fluid condensation. Empirically controlling the heating temperature and time can lead to differences in therapeutic effects or even out of control.
- the heating temperature and time are controlled, if the tube wall shrinks in advance, continued heating may cause damage to the blood vessel and carbonization, and may also make the ablation probe stick to the inner wall of the blood vessel and cannot be pulled out, causing medical accidents; and the heating time is too short It will lead to inadequate treatment, incomplete closure of blood vessels, failure to achieve the purpose of surgery and failure.
- the blood vessel's own condition and surrounding environment are different and variable during the treatment. For example, although the doctor will try to expel the blood in the blood vessel to be treated through pressing and swelling anesthesia, there will still be unequal amounts of blood left in the blood vessel, surrounding the heating element, forming an additional load and cooling the heating element. Obviously, it takes longer to heat to obtain the same effect as without additional blood residue.
- different blood vessel segments of different patients or different blood vessel segments of the same patient may have different sizes and thicknesses.
- the unified heating time control cannot take into account various situations, resulting in the final result: either insufficient heating to achieve the expected ablation effect, or excessive heating causing tissues such as blood vessels to stick to the surface of the thermal ablation probe.
- the root cause of these problems is that temperature and heating time cannot only determine the treatment effect, but are only indirectly related to the treatment effect.
- the parameters that really need to be monitored and controlled during treatment are the distance from the wall of the tubular organ to the surface of the thermal ablation probe and the degree of coagulation of the body fluid around the probe.
- the first embodiment of the present application relates to a radio frequency thermal ablation system, the structure of which is shown in FIG. 1.
- the radio frequency thermal ablation system includes a thermal ablation probe and a radio frequency generator
- the thermal ablation probe includes an insulating heating winding with inductive characteristics
- the radio frequency generator is used to transfer the thermal ablation probe to the The insulated heating winding outputs radio frequency power for heating.
- the inductance characteristic is used to configure the frequency operating point during detection and enhance the sensitivity of detecting parasitic capacitance between winding turns.
- the overall schematic diagram of the exemplary radio frequency thermal ablation probe includes a buffer ring 205 and an ablation body 201 as an effective treatment area.
- the ablation body 201 includes a heating element 202, The tube body 203 and the mobile positioner 204, wherein the heating element 202 is a closed and externally insulated winding with inductance characteristics, which is connected to the tube body 203, and the mobile positioner 204 is sheathed outside the tube body 203.
- insulated heating windings can prevent the current on the windings from directly entering human tissues. It can be understood that the insulated heating winding with inductance characteristics and the tube body in this embodiment may be fixedly connected or may be connected in any other reliable manner.
- the example radio frequency thermal ablation probe may also include a 205 buffer ring, a handle button 206, a handle 207, an inner tube connector 208, a wire 209, and a wire connector 210.
- the radio frequency thermal ablation probe involved in this embodiment may be an improvement of any known radio frequency thermal ablation probe.
- the insulated heating winding with inductance characteristics is an insulated heating winding with weak inductance characteristics.
- the insulated heating winding can be configured to include a first part of a double-strand overlapping resistive winding 302, and a second part of a single-strand spiral inductive winding 301 and The third part of the single-strand spiral inductive winding 2303.
- This centralized winding method makes the winding inductance distribution more concentrated, which can focus and target heating.
- the inductance distribution of the latter is relatively scattered, basically covering all heating elements, and lacking pertinence.
- the number and arrangement of inductive windings and resistive windings can be set accordingly.
- the radio frequency thermal ablation system also includes an inter-lap parasitic capacitance monitoring device, which is used to monitor the change of the parasitic capacitance between the inter-laps during the heating process, and then calculate the degree of contraction of the tubular organ wall and the degree of coagulation of surrounding body fluid .
- the parasitic capacitance monitoring device between turns takes advantage of the resonance characteristics of the insulation heating winding inductance and the capacitance between turns, locates the frequency operating point near the resonance frequency, and calculates the parasitic capacitance value between turns through the phase difference of the voltage and current applied to the winding. For example, considering that the insulation heating winding model near the resonance point can be converted into an RLC equivalent circuit, and the phase difference between the voltage and current is PH, the equivalent capacitance value can be calculated using the following formula:
- L can obtain the equivalent capacitance value by detecting the phase.
- the relationship between the value of the parasitic capacitance between the circles and the degree of contraction of the tubular organ wall and the degree of body fluid condensation can be calibrated in advance through experiments. Near the resonance point, ⁇ PH/ ⁇ f is the largest, and the detection sensitivity is the highest. The detection sensitivity can be improved by configuring the frequency operating point of detection C to near the resonance point by preset L value.
- the inter-loop parasitic capacitance monitoring device can be an independent component, or it can be combined with other components. For example, it can be combined with a radio frequency generator as a part of the radio frequency transmitter.
- the reasons for the change in the complex impedance of the insulation heating winding of the thermal ablation probe involved in the present application include one or a combination of the following: 1The tube wall of the thermally ablated tubular organ shrinks and approaches the surface of the thermal ablation probe; 2The thermal ablation probe The body fluid on the outside gradually solidified.
- the inter-circle parasitic capacitance can be further formed, for example, by the tubular organ pipe wall and solidified body fluid and the part of the inductive winding of the above-mentioned example insulation heating winding.
- the parasitic capacitance between the circles Becomes larger, and then gradually resonates with the inductance of the insulated heating winding.
- the inter-lap parasitic capacitance monitoring device can monitor the change process during the heating process to determine and control the degree of treatment.
- the inductance of the insulated heating winding can be preset as required.
- the inductance of the inductive winding of the insulated heating winding can be preset according to the following formula (2):
- N is the number of winding turns
- D is the winding diameter
- d is the wire diameter
- ⁇ 0 is the vacuum permeability
- ⁇ r is the relative permeability, which is close to 1 in body fluids. Therefore, the inductance value can be controlled by controlling the conductor diameter d and the gap between the winding turns.
- the capacitance between the winding turns can be estimated according to the following formula (3):
- ⁇ 0 is the dielectric constant
- p is the gap between the turns
- D is the winding diameter
- d is the wire diameter
- N is the number of winding turns. Therefore, the larger the winding gap, the smaller the parasitic capacitance between turns.
- the range of parasitic capacitance between turns can be controlled by adjusting the winding parameters according to this rule.
- the inter-turn spacing of the insulated heating winding may satisfy the following conditions: the resonance frequency corresponding to the combination of the inductance of the insulated heating winding and the expected inter-turn parasitic capacitance is within the operating frequency range, wherein the expected inter-turn parasitic The capacitance is the parasitic capacitance between the turns of the insulating heating winding when the distance between the blood vessel tissue and the thermal ablation probe is within a predetermined range.
- the radio frequency thermal ablation system may further include a memory for storing a pre-calibrated resonance frequency, and the pre-calibrated resonance frequency can be used as the target resonance frequency for the control device to read when used.
- a uniform average value can be used, or each thermal ablation probe can be tested and calibrated separately, and finally saved in the memory.
- FIG. 12 shows a test of one embodiment of the calibration process, wherein, after the calibration of the actual test of bonding tubular organ resonance frequency as the control means reads the target resonance frequency f r stored in the memory for use.
- the types of the above-mentioned memory are various.
- it can be EEPROM, or it can be FLASH memory.
- the example A is used for illustration.
- the details listed in the example A are mainly for ease of understanding and are not considered as a reference to this application. Limitation of the scope of protection.
- the distal cross-sectional view of the example thermal ablation probe used is shown in Figure 4.
- the distal end of the example thermal ablation probe includes LED 401, catheter end seal 402, winding carrier tube 403, and insulating heating winding 404, insulating sleeve 405, UV glue 406, capped tube 407, lumen tube 408, tube sleeve 409 and LED wire 410.
- Figure 4 shows a possible way to achieve a closed and externally insulated insulated heating winding, in which winding current does not enter the surrounding tissue.
- the tube wall of the tubular organ shrinks and approaches the surface of the insulating heating winding, while the body fluid 503 in the tubular organ such as blood outside the insulating heating winding gradually solidifies. Further, as shown in FIG.
- the change of 602 can reversely deduct the degree of atrophy of the external organ wall of the probe and/or the degree of body fluid coagulation.
- the insulating sleeve 405 is interposed between the insulating heating winding 404 and the wall (502 or 601) of the tubular organ, which is not shown in FIG. 6. The thinner the insulating sleeve 405 has a smaller effect on the parasitic capacitance between the turns.
- ultra-thin FEP pipes with a wall thickness of less than 0.01 mm, which not only meets the insulation and sealing properties, but also meets the sensitivity to complex impedance perception.
- the degree of shrinkage of the tubular organ and/or the degree of liquid solidification deepens, it gradually resonates with the inductance of the insulating heating winding.
- the phase change rate of the complex impedance of the winding near the resonance point is higher, and the detection is more sensitive.
- the impedance of the insulated heating winding of this example undergoes a trajectory change in the complex plane as shown in Figure 7, where the impedance at the beginning of the treatment is at the position 701 in the complex space.
- the inductance of the insulated heating winding and the parasitic capacitance between the turns resonate Towards a purely resistive position 702.
- the device for monitoring the parasitic capacitance between the windings can monitor the change of the parasitic capacitance between the windings of the insulation heating winding by detecting the vector voltage and current of the insulation heating winding.
- a possible implementation is to sample 32 points of the current and voltage waveforms of the insulation heating winding with a fixed phase. The 32 points can be distributed in a cycle at equal intervals, or it can be a synchronous out-of-phase under-sampling method. The walk is sampled in several adjacent cycles and then assembled into a sampling signal of one cycle.
- the sampling period of 32 sampling points that divide a period of a periodic signal with a frequency of f is originally required to be f/32, and the sampling period can be reduced to 7f/32, that is, reduced by 7 times, the sampling points of the original cycle are scattered to 7 cycles, and the 32 samples formed are S1 to S32.
- the beneficial effect of this is that the sampling frequency and hardware cost are reduced.
- the sampling rate changes with the change of the main clock frequency. When the output frequency changes, the fixed sampling rate and strict synchronization of the sampling to the RF output signal are still maintained.
- the phase difference PH can be calculated in real time using the sampled voltage and current signals in one to several signal cycles, and then the parasitic capacitance between the turns can be calculated.
- the radio frequency thermal ablation system further includes a control device for controlling the radio frequency power output from the radio frequency generator to the insulating heating winding according to the change in the complex impedance detected by the parasitic capacitance monitoring device between the turns. For example, when the complex impedance is close to the preset value, it is judged that the tubular organ wall is shrinking close to the ablation probe.
- the control device can reduce the power output and reduce the shrinkage speed of the tube wall, thereby controlling the treatment effect more smoothly and accurately.
- the control device can be an independent component, or it can be combined with other components, for example, it can be integrated with the parasitic capacitance monitoring device between circles and the radio frequency generator.
- control device is also used to calculate the insulation heating winding complex impedance based on the vector voltage and current of the insulation heating winding detected by the inter-turn parasitic capacitance monitoring device, and extract the phase of the insulation heating winding complex impedance, Obtain the parasitic capacitance between the insulation heating windings, and calculate the distance between the organ tube wall and the degree of condensation of the surrounding body fluid based on this.
- control the RF transmitter to reduce the output power and slow down the organ wall atrophy Speed, when the tube wall distance or the degree of body fluid condensation calculated based on the parasitic capacitance between the insulation heating winding coils reaches a preset threshold, indicating that the organ tube wall shrinks in place and stops outputting radio frequency power to the insulation heating winding.
- control device is also used to search and adjust the working frequency of the radio frequency power output by the radio frequency generator in a preset working frequency range, so that the working frequency dynamically tracks the resonance frequency of the complex impedance, so that the difference The value is less than a predetermined threshold.
- the sensing circuit has better sensitivity to phase detection near the phase of zero.
- the working frequency should be as close as possible to the resonance frequency of the complex impedance, and it is best to be equal. Because the resonance frequency changes with the parasitic capacitance between the turns, it is more difficult to achieve absolute equality, which is more practical.
- the method is to ensure that the difference between the working frequency and the resonance frequency of the complex impedance is less than a predetermined threshold.
- dynamic tracking can make the difference less than 2 degrees stable.
- the organ tube wall shrinks and the resonant frequency moves.
- the output frequency can follow the movement to obtain the best sensitivity until the parasitic capacitance value between the circles enters the preset interval, and the controller reduces until the power output stops.
- the operating frequency range covers the phase change range of the complex impedance of the insulation heating winding from 90 degrees to -90 degrees, corresponding to the designed inductance of the insulation heating winding and the parasitic capacitance between winding turns The working frequency band where resonance occurs.
- the inter-turn capacitance and inductance of the insulated heating winding are relatively weak.
- the parasitic impedance except the insulated heating winding can be pre-calibrated, and the software can be used to monitor the parasitic capacitance between the windings in real time. Algorithm offset
- the inter-turn capacitance and inductance of the insulated heating winding are relatively weak, and the parasitic capacitance (circuit capacitance) of the instrument circuit, wire, etc. is generally greater than the parasitic capacitance between the winding turns.
- the circuit capacitance directly affects the measured frequency characteristic shape of the complex impedance curve as shown in Fig. 8, so that the overall phase lag is shifted, and the criterion that 0 degree is the resonance point is no longer valid.
- the probe handle linkage switch design of Figure 11 can provide a mechanism to effectively offset the circuit capacitance.
- a precision calibration resistor is placed in the handle. The linkage switch controls the output switch and the calibration switch at the same time.
- the linkage switch 1 When the linkage switch 1 is opened, the linkage switch 2 is closed, and the precision calibration resistor is connected to the power output circuit. At the same time, the probe winding is disconnected. The sampling circuit performs a precise calibration of the known resistance. Test resistance and unknown circuit parasitic capacitance for measurement.
- the linkage switch 1 When the linkage switch 1 is closed, the linkage switch 2 is disconnected, the circuit parasitic capacitance and the winding are connected to the output circuit together, and the DSP cancels the influence of the circuit parasitic capacitance through calculation.
- Figure 9 shows the impedance characteristics of the inductance of the insulated heating winding and the parasitic capacitance between the turns near the resonance point.
- the control device can fine-tune the radio frequency generation in real time according to the detection result of the parasitic capacitance monitoring device between the turns.
- the working frequency of the radio frequency power emitted by the device keeps working at the insulation heating winding impedance target control point 801 in FIG. 8 until the working frequency approaches the initial working frequency of the insulation heating winding.
- FIG. 10 it is a radio frequency thermal ablation system with an exemplary radio frequency generator circuit block diagram.
- the components and details in the circuit block diagram of the example radio frequency generator are only one of various radio frequency generator implementation modes, and are not limited to this. It can be understood that, in some embodiments, the radio frequency generator may be implemented in other forms of hardware and/or software.
- the second embodiment of the present application relates to a control method of a radio frequency thermal ablation system.
- the radio frequency thermal ablation system includes a thermal ablation probe and a radio frequency generator, wherein the thermal ablation probe includes an insulating heating winding with inductance characteristics, and the radio frequency generator is used to output radio frequency power for heating to the insulating heating winding.
- the inductance characteristic is used to configure the frequency operating point during detection and enhance the sensitivity of detecting parasitic capacitance between winding turns.
- the radio frequency thermal ablation system involved in this embodiment may be the radio frequency thermal ablation system of the first embodiment, and the technical details of the radio frequency thermal ablation system involved in the first embodiment can be applied to this embodiment.
- Fig. 11 is a schematic flowchart of a control method based on the above radio frequency thermal ablation system. As shown in FIG. 10, the control method of the radio frequency thermal ablation system may specifically include the following steps:
- step 1001 the radio frequency generator outputs radio frequency power for heating to the insulated heating winding.
- step 1002 is entered to monitor the change in parasitic capacitance between the insulating heating coils caused by the tubular organ wall approaching the insulating heating winding and/or the solidification of body fluid during the heating process. Specifically, the phase change of the current and voltage of the insulation heating winding is monitored during the heating process, and the parasitic capacitance between the winding turns is calculated.
- the reasons for the change in the complex impedance of the insulation heating winding of the thermal ablation probe include one of the following 12 or a combination thereof: 1 the tube wall of the thermally ablated tubular organ shrinks and approaches the surface of the thermal ablation probe; 2 the body fluid outside the thermal ablation probe Gradually solidify.
- step 1002 it may further include the following step: dynamically searching and adjusting the working frequency of the radio frequency power output by the radio frequency generator in a preset working frequency range, so that the working frequency is in resonance with the complex impedance The difference in frequency is less than a predetermined threshold.
- the operating frequency range covers the range of the phase of the complex impedance of the insulating heating winding from 90 degrees to -90 degrees.
- the parasitic impedance except the insulation heating winding can be pre-calibrated during production or use, and the parasitic capacitance between the winding turns can be offset by the software algorithm when monitoring the parasitic capacitance between the winding turns in real time.
- the parasitic capacitance of the circuit calibrated during production is Cp.
- Cp and the insulation heating winding are in parallel. The current flowing through Cp is
- the output voltage is Vo
- Ip is the current of the parasitic capacitance of the circuit
- Io is the total output current.
- the current Ih that actually flows through the insulation heating winding is
- the parasitic capacitance between the turns is calculated according to the variation range of the relationship between Ih and Vo from 90 degrees to -90 degrees.
- control the amount of radio frequency power output to the insulation heating winding can be used.
- PID Proportional Integral Difference
- controlling the radio frequency power output to the insulation heating winding may further include the following steps i, ii, iii: i. Obtain the vector voltage and current of the insulation heating winding; ii. Calculate based on the vector voltage and current The insulation heating winding complex impedance, extract the phase of the insulation heating winding complex impedance; iii.
- the inter-turn spacing of the insulating heating winding satisfies the following condition: the resonance frequency corresponding to the combination of the inductance of the insulating heating winding and the expected inter-turn parasitic capacitance is within the operating frequency range, wherein the expected inter-turn parasitic capacitance It is the parasitic capacitance between the turns of the insulating heating winding when the distance between the blood vessel tissue and the thermal ablation probe is within a predetermined range.
- the resonance frequency can be calibrated in advance. Because of the correspondence between the parasitic capacitance and the resonance frequency between the insulation heating windings, the resonance frequency can be indirectly used as the detection and control target.
- Figure 13 shows the test calibration process of an embodiment. After the calibration of the test, the actual tubular organ of bonding a target resonance frequency f r the resonant frequency stored in the control device for use in a memory read.
- Figure 14 (A) shows the case of a thermal ablation probe with a memory.
- the calibrated and stored tubular organs of each probe are fitted to the target resonance frequency fr as the target output frequency of the radio frequency generator to control the entire treatment process.
- Figure 14(B) shows the case where the thermal ablation probe has no memory, and a unified nominal frequency is used as the target output frequency of the radio frequency generator to control the entire treatment process.
- an act is performed based on a certain element, it means that the act is performed at least based on that element, which includes two situations: performing the act only based on the element, and performing the act based on the element and Other elements perform the behavior.
- Multiple, multiple, multiple, etc. expressions include two, two, two, and two or more, two or more, and two or more expressions.
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Abstract
一种射频热消融***及其控制方法,射频热消融***包括:热消融探头,热消融探头包括带电感特性的绝缘加热绕组(404),其电感特性用于配置检测时的频率工作点,增强检测绕组圈间寄生电容(602)的灵敏度;射频发生器,用于向绝缘加热绕组(404)输出用于加热的射频功率;圈间寄生电容(602)监测装置,用于在加热过程中监测因管状器官壁(502,601)接近绝缘加热绕组(404)和/或体液(503)凝固产生的绕组圈间寄生电容(602)的变化;控制装置,用于根据圈间寄生电容(602)监测装置检测到的圈间寄生电容(602)的变化,控制射频发生器向绝缘加热绕组(404)输出的射频功率大小。
Description
本申请涉及消融技术,特别涉及射频热消融技术。
射频消融技术是一种应用较为广泛的现代微创技术。近年来,射频消融被应用于心脏、癌症肿瘤、乃至皮肤等多种病灶组织。射频热消融技术是射频能量不直接进入人体,而是在器械内部产生热能,再将热能传递到人体产生热消融效果。由于这种技术对人体的创伤较小,同时消融方式可以由电子***精确控制,因此成为现代有源微创手术中被采用较多的一种技术。例如目前用射频消融探头消融支气管神经以治疗哮喘,经过尿道消融***组织来治疗***肥大,消融外周血管使其萎缩,消融食道表面组织来治疗食道癌,消融子宫表面组织来治疗子宫癌,等等。人体的这些器官,例如血管、支气管、尿道、食道、子宫等基本呈细长管状结构,对射频探头在外形、功能和性能上的要求有其共性。
目前,血管热消融技术依靠一定温度下调节加热时间来控制血管收缩程度。射频热消融探头多采用封闭且对外绝缘的阻性加热元件,如专利US7837677,EP1906853,US2017/0202600A1,EP2662044,US10357305等,特点是绕组不和人体组织构成电流回路,因此本领域通常做法是忽略外部组织对阻性绕组特性的影响,只依靠简单的温度反馈控制进行治疗。
但是,单纯的对温度和时间的控制方式并不能获得理想的射频热消融效果。例如热消融加热的区域一般不仅仅是一个点,而是一块区域。限于工程实现条件和成本的限制,一般不可能在整个消融区域布置密集的温度传感点,这导致局部治疗区域温度可能超出目标温度。最典型的情况是在感知手段不足的情况下器官壁由于意外高温贴紧到加热绕组表面后由于缺乏有效感知手段治疗仍然继续,导致黏粘乃至碳化,甚至引发医疗事故。
发明内容
本申请的目的在于提供一种射频热消融***及其控制方法,能够利用封闭绕组的圈间寄生电容对在热消融过程中对管状器官孔径收缩的状态进行监测,进而通过设计绕组感性来配置监测工作点、增强对圈间寄生电容的感知灵敏度,从而有效地控制治疗过程,使得热消融治疗过程中关键的治疗参数如器官管壁距离可控,更安全、消融深度控制更准确。
本申请公开了一种射频热消融***,包括:
热消融探头,所述热消融探头包括带电感特性的绝缘加热绕组,该电感特性用于配置检测时的频率工作点,增强检测绕组圈间寄生电容的灵敏度;
射频发生器,用于向所述加热绕组输出用于加热的射频功率;
圈间寄生电容监测装置,用于在加热过程中监测因管状器官壁接近绝缘加热绕组和/或体液凝固产生的所述绝缘加热绕组圈间寄生电容的变化;
控制装置,用于根据所述圈间寄生电容监测装置检测到的圈间寄生电容的变化,控制所述射频发生器向所述加热绕组输出的射频功率大小。
在一个优选例中,所述圈间寄生电容监测装置通过检测所述加热绕组的矢量电压和电流,监测所述加热绕组圈间寄生电容的变化。
在一个优选例中,所述控制装置还用于,根据所述圈间寄生电容监测装置检测到的所述加热绕组的矢量电压和电流计算所述加热绕组圈间寄生电容,并提取所述加热绕组圈间寄生电容和绕组电感特性合成后的阻抗相位,如果所述相位进入预设区间,则控制所述射频发射器停止向所述加热绕组输出射频功率。
在一个优选例中,所述控制装置输出频率连续可调;所述控制装置还用于,在预先设定的工作频率范围,搜索和调整所述射频发生器输出的射频功率的工作频率,使得该工作频率与所述复阻抗的共振频率的差值小于预定门限。
在一个优选例中,在抵消电路寄生电容后,所述工作频率范围覆盖所述加热绕组复阻抗的相位从90度到-90度的变化范围。
在一个优选例中,所述加热绕组的圈间间距满足以下条件:使得该加热 绕组的电感和预期圈间寄生电容的组合所对应的共振频率在所述工作频率范围内,其中所述预期圈间寄生电容是血管组织与所述热消融探头的距离在预定范围内时所述加热绕组的圈间寄生电容。
在一个优选例中,还包括存储器,用于存储预先标定的共振频率,作为目标共振频率供使用时所述控制装置读取。
本申请还公开了一种射频热消融***的控制方法所述射频热消融***包括:热消融探头,所述热消融探头包括带电感特性的绝缘加热绕组,该电感特性用于配置检测时的频率工作点,增强检测绕组圈间寄生电容的灵敏度;射频发生器,用于向所述绝缘加热绕组输出用于加热的射频功率;所述方法包括:
所述射频发生器向所述绝缘加热绕组输出用于加热的射频功率;
在加热过程中监测所述因管状器官壁接近绝缘加热绕组和/或体液凝固产生的所述绝缘加热绕组圈间寄生电容的变化;
根据检测到的圈间寄生电容的变化,控制所述射频发生器向所述绝缘加热绕组输出的射频功率大小。
在一个优选例中,所述在加热过程中监测所述绝缘加热绕组圈间寄生电容的变化,进一步包括:
通过检测所述加热绕组的矢量电压和电流,监测所述加热绕组圈间寄生电容的变化;
所述根据所述圈间寄生电容监测装置检测到的圈间寄生电容的变化,控制所述射频发生器向所述加热绕组输出的射频功率大小,进一步包括:
根据检测到的所述加热绕组的矢量电压和电流计算所述加热绕组圈间寄生电容,并提取所述加热绕组圈间寄生电容和绕组电感特性合成后的阻抗相位,如果所述相位进入预设区间,则控制所述射频发射器停止向所述加热绕组输出射频功率。
在一个优选例中,所述在加热过程中监测所述绝缘加热绕组复阻抗的变化之后,还包括:
在预先设定的工作频率范围,搜索和调整所述射频发生器输出的射频功率的工作频率,使得该工作频率与所述复阻抗的共振频率的差值小于预定门 限。
本申请实施方式中,考虑到在热消融治疗过程中管状器官自身状况及周围环境可变性,首先根据治疗过程中绕组圈间寄生电容的范围为热消融探头设计带电感特性的绝缘加热绕组,该带电感特性的绝缘加热绕组采用集中式绕制方式,使得该绝缘加热绕组的电感分布较集中,可以集中针对性地传感加热。在热消融治疗过程中,该被热消融的管状器官管壁及凝固的体液和该绝缘加热绕组的感性部分会形成圈间寄生电容,并且随着管状器官萎缩程度及液体凝固程度的加深,该圈间寄生电容逐渐增大,在这一过程中,圈间寄生电容和绝缘加热绕组电感趋近于共振,其整体复阻抗的相位变化相对于频率的变化率逐渐增大,因此检测整体复阻抗相位的灵敏度提高,进而使得根据复阻抗相位推算圈间寄生电容的灵敏度提高。本申请实施方式中,通过在绝缘加热绕组中设计电感因素,可以提高在热消融过程中对圈间寄生电容的实时检测能力。因此监控热消融治疗过程的该带感性的绝缘加热绕组的复阻抗的变化可以更准确地监测和控制圈间寄生电容,进而更准确地推算和控制器官壁逼近热消融探头的程度和周围体液凝结的程度。在治疗过程中,可以根据监测结果来实时地控制和优化热消融治疗过程,例如当复阻抗的接近预设值时,判断管状器官壁萎缩接近消融探头,控制装置可减小功率输出,降低管壁的萎缩速度,从而更平缓精确地控制治疗效果。
进一步地,因为传感电路在相位接近0的附近对相位检测有更好的灵敏度,本申请的实施方式中,在预先设定的工作频率范围,搜索和调整该射频发生器输出的射频功率的工作频率,使得该工作频率与该复阻抗的共振频率的差值小于预定门限;进一步通过设置该绝缘加热绕组的圈间间距来使得该绝缘加热绕组的电感和预期圈间寄生电容的组合所对应的共振频率在该工作频率范围内,其中该预期圈间寄生电容是血管组织与该热消融探头的距离在预定范围内时该绝缘加热绕组的圈间寄生电容,从而提高监测和控制的灵敏度,使得最终的热消融治疗效果更佳。
本申请的说明书中记载了大量的技术特征,分布在各个技术方案中,如果要罗列出本申请所有可能的技术特征的组合(即技术方案)的话,会使得说明书过于冗长。为了避免这个问题,本申请上述发明内容中公开的各个技术特征、在下文各个实施方式和例子中公开的各技术特征、以及附图中公开 的各个技术特征,都可以自由地互相组合,从而构成各种新的技术方案(这些技术方案均应该视为在本说明书中已经记载),除非这种技术特征的组合在技术上是不可行的。例如,在一个例子中公开了特征A+B+C,在另一个例子中公开了特征A+B+D+E,而特征C和D是起到相同作用的等同技术手段,技术上只要择一使用即可,不可能同时采用,特征E技术上可以与特征C相组合,则,A+B+C+D的方案因技术不可行而应当不被视为已经记载,而A+B+C+E的方案应当视为已经被记载。
图1是根据本申请第一实施方式的射频热消融***结构示意图;
图2是根据本申请第一实施方式的示例射频消融探头整体示意图;
图3是根据本申请第一实施方式的一个实施例的绝缘加热绕组绕制方式的示意图;
图4是根据本申请第一实施方式的示例A中示例射频消融探头远端剖面示意图;
图5是根据本申请第一实施方式的示例A中热消融时管状器官内壁贴近示例射频消融探头表面的示意图;
图6是根据本申请第一实施方式的示例A中示例绝缘加热绕组和管状器官内壁形成圈间寄生电容的示意图;
图7是根据本申请第一实施方式的示例A中的热消融治疗过程中圈间寄生电容的变化引起示例绝缘加热绕组复阻抗变化趋势示意图;
图8是根据本申请第一实施方式的示例A中示例绝缘加热绕组的电压和电流低频采样方法示意;
图9是根据本申请第一实施方式的示例A中示例绝缘加热绕组的电感和圈间寄生电容在共振点附近的阻抗特性示意;
图10是根据本申请第一实施方式的具有示例射频发生器电路框图的射频热消融***结构示意图;
图11是根据本申请第一实施方式的电路寄生电容标定机制示意图;
图12是根据本申请第二实施方式的射频热消融***的控制方法的流程示意图;
图13是根据本申请的共振频率的标定过程流程示意图;
图14(A)是根据本申请的热消融探头带存储器的情况下采用每只探头经标定存储的管状器官贴合目标共振频率f
r作为射频发生器的目标输出频率以控制整个治疗过程的流程示意图;
图14(B)是根据本申请的热消融探头不带存储器的情况采用统一的标称频率作为射频发生器的目标输出频率以控制整个治疗过程的流程示意图。
其中,
201-消融本体 202-加热元件
203-管体 204-移动***
205-缓冲圈 206-手柄按钮
207-手柄 208-内管接头
209-导线 210-导线接头
301-感性绕组1 302-阻性绕组
303-感性绕组2 304-叠绕方式感性绕组
305叠绕方式阻性绕组 401-LED
402导管端部封胶
403-绕组载管 404-绝缘加热绕组
405-绝缘套管 406-UV胶
407-封端管 408-内腔管
409-管体套管 410-LED导线
501-热消融时管状器官收缩到治疗探头 502-管状器官管壁
503-管状器官内体液 602-圈间寄生电容
701-治疗开始时示例绝缘加热绕组的阻抗在复空间的位置
702-治疗后示例绝缘加热绕组的电感和圈间寄生电容共振趋向纯阻性
801-示例绝缘加热绕组阻抗目标控制点
在以下的叙述中,为了使读者更好地理解本申请而提出了许多技术细节。但是,本领域的普通技术人员可以理解,即使没有这些技术细节和基于以下各实施方式的种种变化和修改,也可以实现本申请所要求保护的技术方案。
部分概念的说明:
消融:施加能量或物质令人体器官变性,达到治疗效果。
热消融:施加热能的消融技术。
射频发射器:能发生和控制高频信号的电子仪器,在消融应用上配合消融探头,将射频能量发送到消融探头,起到消融治疗效果。
复阻抗:考虑电压和电流相位差计算得到的阻抗,包括实部和虚部。
肿胀麻醉:在病人体内注入麻醉液,对器官形成麻醉的同时形成肿胀压迫,在血管消融时达到辅助效果。
EEPROM:Electrically Erasable Programmable read only memory,带电可擦可编程只读存储器。
为使本申请的目的、技术方案和优点更加清楚,下面将结合附图对本申请的实施方式作进一步地详细描述。
目前,血管热消融技术一般依靠一定温度下调节加热时间来控制血管收缩程度。因此目前市场上的治疗器械一般控制的是两个参数:加热温度和加热时间。这两者和治疗时需要控制的参数如管壁收缩程度或体液凝结程度间接相关,简单而言加热时间越长,血管收缩程度越高。但是,因为器官形状尺寸各异,加热时间和温度不能唯一确定器官壁收缩程度或体液凝结程度,经验性地控制加热温度和时间会导致治疗效果的差异甚至失控。例如在加热温度和时间受控的情况下,如果管壁提前收缩,继续加热可能会导致血管受损碳化,也可能使得消融探头粘到血管内壁无法拔出,造成医疗事故;而加热时间过短则会导致治疗不充分,血管没有完全闭合,达不到手术目的从而 失败。而且,在治疗过程中血管的自身状况及周围环境是不同而且是可变的。例如虽然医生会企图通过按压和肿胀麻醉排出待治疗血管中的血液,血管中还是会留有不等量的血液,围绕在加热元件附近,形成额外负载并会对加热元件冷却。有额外血液残余的情况显然需要更长时间加热才能获得与无额外血液残余情况下的相同效果;又例如不同的病人的不同血管段或者同一个病人的不同血管段都可能会出现大小厚薄不一的情况,统一的加热时间控制并不能兼顾各种情况,导致最后的结果是:要么加热不足而不能达到预期的消融效果,要么加热过度而使得血管等组织粘到热消融探头表面。出现这些问题的根本原因是,温度和加热时间不能唯一决定治疗效果,而只是和治疗效果间接相关。治疗时真正需要监测和控制的参数是管状器官壁到热消融探头表面的距离和探头周围体液的凝结程度。
因此,针对上述情况,本申请的第一实施方式涉及一种射频热消融***,其结构如图1所示。
具体地说,如图1所示,首先,该射频热消融***包括热消融探头和射频发生器,该热消融探头包括带电感特性的绝缘加热绕组,该射频发生器用于向该热消融探头的绝缘加热绕组输出用于加热的射频功率。在一个实施例中,该电感特性用于配置检测时的频率工作点,增强检测绕组圈间寄生电容的灵敏度。
在一个实施例中,如图2所示的示例射频热消融探头的整体示意图,该示例射频热消融探头包括缓冲圈205和作为有效治疗区域的消融本体201,该消融本体201包括加热元件202、管体203和移动***204,其中加热元件202为封闭和对外绝缘且带电感特性的绕组,与管体203连接,管体203外部套装有移动***204。采用绝缘加热绕组可以避免绕组上的电流直接进入人体组织。可以理解,该实施例中的带电感特性的绝缘加热绕组与管体可以是固定连接或者可以是任何其他可靠连接方式。除此之外,该示例射频热消融探头还可以包括205缓冲圈、206手柄按钮、手柄207、内管接头208、导线209和导线接头210等。在某些实施例中,本实施方式涉及的射频热消融探头可以是对任何已知的射频热消融探头的改良。
可选地,该带电感特性的绝缘加热绕组是带弱感特性的绝缘加热绕组。该带弱感特性的绝缘加热绕组的实现方式有多种。在一个实施例中,如图3右半侧图所示,该绝缘加热绕组可以设置为包括第一部分的双股重叠的阻性 绕组302,以及第二部分的单股螺旋的感性绕组1 301和第三部分的单股螺旋的感性绕组2 303,此集中式绕制方式使得绕组电感分布较集中,可以集中针对性地传感加热。与图3的左半侧图叠绕方式(叠绕方式感性绕组304+叠绕方式阻性绕组305)相比,后者的电感分布比较分散,基本覆盖全部加热元件,缺少针对性。在某些实施例中,感性绕组和阻性绕组的数量和排布方式可以根据情况进行相应设定。
进一步地,该射频热消融***还包括圈间寄生电容监测装置,该圈间寄生电容监测装置用于在加热过程中监测圈间寄生电容的变化,进而推算管状器官壁收缩程度和周围体液凝固程度。圈间寄生电容监测装置利用绝缘加热绕组电感和圈间电容共振特点,将频率工作点定位到共振频率附近,通过施加在绕组上的电压和电流的相位差计算圈间寄生电容值。例如考虑到共振点附近绝缘加热绕组模型可以转换为RLC等效电路,其上电压和电流的相位差为PH,则可利用下式推算等效电容值:
tan(PH)=(XL–XC)/R (1)
其中XL为感抗,XL=2πfL,XC为容抗,XC=1/(2πfC),f为工作频率,R为等效电阻。因此已知L可通过检测相位获得等效电容值。而圈间寄生电容值和管状器官壁收缩程度和体液凝结程度的对应关系可事先通过试验标定。在共振点附近,ΔPH/Δf最大,检测灵敏度最高,可通过预设L值将检测C的频率工作点配置到共振点附近来提高检测灵敏度。圈间寄生电容监测装置可以是一个独立的部件,也可以和其他的部件组合在一起,例如可以和射频发生器组合在一起,作为射频发射器的一部分。
可选地,本申请涉及的热消融探头的绝缘加热绕组复阻抗的变化的原因包括以下之一或其组合:①被热消融的管状器官管壁萎缩,逼近热消融探头表面;②热消融探头外侧的体液逐渐凝固。基于此,进一步地可以例如通过管状器官管壁及凝固的体液和上述示例绝缘加热绕组的感性绕组的部分形成圈间寄生电容,由于随着萎缩程度及液体凝固程度的加深,该圈间寄生电容变大,进而逐渐和该绝缘加热绕组的电感产生共振,在这个过程中,绝缘加热绕组的复阻抗在复平面上经历由感性趋近于阻性的变化的。所以,该圈间寄生电容监测装置例如可以在加热过程中监测该变化过程来判断和控制治疗程度。
可选地,该绝缘加热绕组的电感可以根据需要进行预先设定,在一个实 施例中,该绝缘加热绕组的感性绕组的电感可以根据以下公式(2)进行预先设定:
其中,N为绕组圈数,D为绕组直径,d为导线直径,μ
0为真空磁导率,μ
r为相对磁导率,在体液内接近1。因此通过控制导体直径d和绕组圈间间隙可以控制电感值。同时,在不考虑外部介质的情况下,该绕组圈间电容可以根据以下公式(3)进行估算:
其中,ε
0为介电常数,p为圈间间隙,D为绕组直径,d为导线直径,N为绕组圈数。因此基本上绕组间隙越大圈间寄生电容越小,原理上可根据此规律通过调节绕组参数控制圈间寄生电容的范围。
进一步地,为了提高灵敏度进而达到更好的监测效果。可选地,该绝缘加热绕组的圈间间距可以满足以下条件:使得该绝缘加热绕组的电感和预期圈间寄生电容的组合所对应的共振频率在该工作频率范围内,其中该预期圈间寄生电容是血管组织与该热消融探头的距离在预定范围内时该绝缘加热绕组的圈间寄生电容。
可选地,该射频热消融***还可以包括存储器,用于存储预先标定的共振频率,该预先标定的共振频率可以作为目标共振频率供使用时该控制装置读取。在该共振频率的标定过程中,例如可以采用统一的平均值,也可以每支热消融探头单独测试标定,并最后保存到存储器中。图12示出了一个实施例的测试标定过程,其中,在测试标定后将实际管状器官贴合时的共振频率作为目标共振频率f
r存储到存储器中供使用时控制装置读取。
上述存储器的种类是多种多样的。例如可以是EEPROM,或者可以是FLASH存储器等。
为了能够更好地理解上述“在加热过程中监测该绝缘加热绕组圈间寄生电容的变化”的过程,通过示例A进行说明,该示例A中罗列的细节主要是为了便于理解,不作为对本申请保护范围的限制。在该示例A中:所使用的示例热消融探头的远端剖面图如图4所示,该示例热消融探头远端包括LED 401、导管端部封胶402、绕组载管403、绝缘加热绕组404、绝缘套管405、UV胶406、封端管407、内腔管408、管体套管409和LED导线410。图4显示了一种可能的封闭和对外绝缘的绝缘加热绕组的实现方式,在此方式下绕组电流不进入周围组织。如图5所示,在使用该示例热消融探头的热消融过程中,管状器官管壁萎缩,逼近绝缘加热绕组表面,同时绝缘加热绕组外侧的血液等管状器官内体液503逐渐凝固。进一步地,如图6所示,该管状器官管壁601及凝固的体液和示例绝缘加热绕组的感性绕组部分形成的圈间圈间寄生电容602,因此通过检测所形成的圈间圈间寄生电容602的变化情况可以反推探头外部器官壁萎缩的程度和/或体液凝固的程度。绝缘套管405介于绝缘加热绕组404和管状器官管壁(502或601)之间,未在图6中显示。绝缘套管405越薄对圈间寄生电容的影响越小。因此我们采用壁厚小于0.01毫米的超薄FEP管材,在满足绝缘性、密封性的同时满足对复阻抗感知的灵敏度。进一步地,随着该管状器官的萎缩程度和/或液体凝固程度的加深,其逐渐和绝缘加热绕组电感共振。而且,在共振点附近绕组的复阻抗相位变化率更高,检测更灵敏。在上述过程中,该示例绝缘加热绕组的阻抗在复平面上经历如图7的轨迹变化,其中治疗开始时的阻抗在复空间的位置701,治疗后绝缘加热绕组的电感和圈间寄生电容共振趋向纯阻性位置702。
可选地,该圈间寄生电容监测装置可以通过检测该绝缘加热绕组的矢量电压和电流,监测该绝缘加热绕组圈间寄生电容的变化。可能的一个实施方式为,以固定相位对绝缘加热绕组的电流和电压波形采样32个点,这32个点可以等间隔分布在一个周期中,也可以是同步异相欠采样方法,将固定相位散步在邻近的几个周期中采样后组装成一个周期的采样信号。如图8所示,对一个频率为f的周期信号的等分一个周期的32个采样点原来需要的采样周期是f/32,在相邻周期变化不剧烈的情况下可以将采样周期降低到7f/32,即降低7倍,原来一个周期的采样点则分散到7个周期,形成的32个采样为S1~S32。完成后需要重新根据相位将采样序列排序组合形成等同于原来信号的一个周期的32等分采样。这样做的有益效果是降低了采样频率和硬件成本,同时采样率随主时钟频率变化而变化,在输出频率变化时仍然保持固定采样率和采样对于射频输出信号的严格同步。
在同步采样前提下,根据离散傅里叶变换的原理获得32个电压和电流采样后按照下式计算相位差:
其中Sk为相位为0的同频方波,k=1~16时Sk=1,k=17~32时Sk=-1;Ck为相位为90度的同频方波,k=1~8时Ck=1,k=9~24时Ck=-1,k=25~32时Ck=1。依靠这种方法可以在一个到数个信号周期中利用采样的电压和电流信号对相位差PH实时计算,进而推算圈间寄生电容。
进一步地,该射频热消融***还包括控制装置,该控制装置用于根据该圈间寄生电容监测装置检测到的复阻抗的变化来控制该射频发生器向该绝缘加热绕组输出的射频功率大小。例如当复阻抗的接近预设值时,判断管状器官壁萎缩接近消融探头,该控制装置可减小功率输出,降低管壁的萎缩速度,从而更平缓精确地控制治疗效果。控制装置可以是一个独立的部件,也可以和其他的部件组合在一起,例如可以和圈间寄生电容监测装置、射频发生器整合在一起。
可选地,该控制装置还用于,根据该圈间寄生电容监测装置检测到的该绝缘加热绕组的矢量电压和电流计算该绝缘加热绕组复阻抗,并提取该绝缘加热绕组复阻抗的相位,得到绝缘加热绕组圈间寄生电容,并据此推算器官管壁距离以及周围体液凝结程度,如果绝缘加热绕组圈间寄生电容进入预设区间,则控制该射频发射器降低输出功率,减缓器官壁萎缩速度,待根据绝缘加热绕组圈间寄生电容推算的管壁距离或体液凝结程度到达预设阈值时、指示器官管壁萎缩到位后停止向该绝缘加热绕组输出射频功率。
可选地,该控制装置还用于,在预先设定的工作频率范围,搜索和调整该射频发生器输出的射频功率的工作频率,使得该工作频率动态跟踪该复阻抗的共振频率,使得差值小于预定门限。这是因为传感电路在相位接近0的附近对相位检测有更好的灵敏度。在一个实施例中,该工作频率应该尽量趋近复阻抗的共振频率,最好是相等,因为共振频率随着圈间寄生电容的变化而变化,所以绝对相等是较难做到的,比较实用的方式是确保该工作频率与复阻抗的共振频率的差值小于一个预定门限,例如实际应用中通过动态跟踪可使得该差值稳定小于2度。随着输出功率和加热,器官管壁萎缩,共振频率发生移动,输出频率可跟随移动以获得最佳灵敏度,一直到圈间寄生电容值进入预设区间,控制器降低直至停止功率输出。
可选地,抵消电路寄生电容后,该工作频率范围覆盖该绝缘加热绕组复 阻抗的相位从90度到-90度的变化范围,对应于所设计的绝缘加热绕组感抗和绕组圈间寄生电容发生共振的工作频段。绝缘加热绕组的圈间电容和电感均比较弱,为排除仪器电路、导线等的寄生电容影响,可对除绝缘加热绕组以外的寄生阻抗进行预先标定,在实时监测绕组圈间寄生电容时用软件算法抵消
绝缘加热绕组的圈间电容和电感均比较弱,仪器电路、导线等的寄生电容(电路电容)一般大于绕组圈间寄生电容。电路电容直接影响所测量到的如图8的复阻抗曲线频率特性形状,使得整体相位滞后偏移,会使得以0度为共振点的判据不再有效。图11的探头手柄联动开关设计可以提供有效抵消电路电容的机制。在手柄中置有精密校验电阻。联动开关同时控制输出开关和校验开关,当联动开关1断开时联动开关2闭合,将精密校验电阻接入功率输出电路,同时断开探头绕组,采样电路对已知阻值的精密校验电阻和未知的电路寄生电容进行测量。当联动开关1闭合时联动开关2断开,电路寄生电容和绕组一起连接到输出电路,DSP通过计算抵消电路寄生电容影响。
继续上述示例A,图9示出了该示例绝缘加热绕组的电感和圈间寄生电容在共振点附近的阻抗特性示意图,该控制装置可以根据该圈间寄生电容监测装置的检测结果实时微调射频发生装置发出的射频功率的工作频率,使得其一直保持在图8的绝缘加热绕组阻抗目标控制点801上工作,一直到工作频率趋近于绝缘加热绕组的初始工作频率中止。
在一个实施例中,如图10所示,为具有示例射频发生器电路框图的射频热消融***。其中该示例射频发生器电路框图中的各组成部分和细节只是各种射频发生器实现方式中的一种,不只限于此。可以理解,在某些实施例中,该射频发生器可以以其他形式的硬件和/或软件实现。
本申请的第二实施方式涉及一种射频热消融***的控制方法。该射频热消融***包括热消融探头和射频发生器,其中该热消融探头包括带电感特性的绝缘加热绕组,该射频发生器用于向该绝缘加热绕组输出用于加热的射频功率。在一个实施例中,该电感特性用于配置检测时的频率工作点,增强检测绕组圈间寄生电容的灵敏度。
可选地,本实施方式涉及的射频热消融***可以是第一实施方式的射频 热消融***,第一实施方式涉及的射频热消融***的技术细节可以应用于本实施方式。
图11是基于上述射频热消融***的控制方法的流程示意图。如图10所示,该射频热消融***的控制方法具体可以包括以下步骤:
在步骤1001中,该射频发生器向该绝缘加热绕组输出用于加热的射频功率。
之后,进入步骤1002,在加热过程中监测所述因管状器官壁接近绝缘加热绕组和/或体液凝固产生的所述绝缘加热绕组圈间寄生电容的变化。具体地说,在加热过程中监测该绝缘加热绕组电流和电压的相位变化,并计算绕组圈间寄生电容。
可选地,该热消融探头绝缘加热绕组复阻抗的变化的原因包括以下①②之一或其组合:①被热消融的管状器官管壁萎缩,逼近热消融探头表面;②热消融探头外侧的体液逐渐凝固。
可选地,该步骤1002之后,还可以包括以下步骤:在预先设定的工作频率范围,动态搜索和调整该射频发生器输出的射频功率的工作频率,使得该工作频率与该复阻抗的共振频率的差值小于预定门限。
可选地,在抵消电路寄生电容后,该工作频率范围覆盖该绝缘加热绕组复阻抗的相位从90度到-90度的变化范围。为排除仪器电路、导线等的寄生电容影响,生产时或使用时可对除绝缘加热绕组以外的寄生阻抗进行预先标定,在实时监测绕组圈间寄生电容时用软件算法抵消。例如生产时标定的电路寄生电容为Cp,计算模型中Cp和绝缘加热绕组为并联关系。流经Cp的电流为
其中输出电压为Vo,Ip为电路寄生电容的电流,Io为输出总电流,则实际流过绝缘加热绕组的电流Ih为
因此抵消电路寄生电容的影响后圈间寄生电容则根据Ih和Vo的关系从90度到-90度的变化范围计算得到。
之后,进入步骤1003,根据检测到的圈间寄生电容的变化(或者说根据绝缘加热绕组圈间寄生电容推算器官管壁萎缩程度和体液凝结程度),控制向该绝缘加热绕组输出的射频功率大小。其控制算法可采用常见的PID(比例积分差分)控制方法等等,针对管壁萎缩程度和体液凝结程度的治疗参数获得连续平滑的控制效果。
可选地,上述步骤1002~步骤1003中的在加热过程中监测该绝缘加热绕组复阻抗的变化,根据检测到的复阻抗的相位变化计算绝缘加热绕组圈间寄生电容,推算器官管壁萎缩程度和体液凝结程度,控制向该绝缘加热绕组输出的射频功率大小可以进一步包括以下ⅰ、ⅱ、ⅲ的步骤:ⅰ.获取该绝缘加热绕组的矢量电压和电流;ⅱ.根据该矢量电压和电流计算该绝缘加热绕组复阻抗,提取该绝缘加热绕组复阻抗的相位;ⅲ.由复阻抗的相位计算绝缘加热绕组圈间寄生电容,根据该电容值调节输出射频功率大小,如果该电容值进入预设区间,则控制该射频发射器停止向该绝缘加热绕组输出射频功率。
可选地,该绝缘加热绕组的圈间间距满足以下条件:使得该绝缘加热绕组的电感和预期圈间寄生电容的组合所对应的共振频率在该工作频率范围内,其中该预期圈间寄生电容是血管组织与该热消融探头的距离在预定范围内时该绝缘加热绕组的圈间寄生电容。
可选地,该共振频率可以预先进行标定。因为绝缘加热绕组圈间寄生电容和共振频率的对应关系,可间接地将共振频率作为检测和控制目标。图13示出了一个实施例的测试标定过程。在测试标定后,将实际管状器官贴合时的共振频率作为目标共振频率f
r存储到存储器中供使用时控制装置读取。
考虑到,可能存在热消融探头带存储器和不带存储器的两种情况,分别按照图14(A)和图14(B)调整射频发生器的输出频率以控制整个治疗过程。图14(A)示出了热消融探头带存储器的情况,采用每只探头经标定存储的管状器官贴合目标共振频率f
r作为射频发生器的目标输出频率以控制整个治疗过程。图14(B)示出了热消融探头不带存储器的情况,采用统一的标称频率作为射频发生器的目标输出频率以控制整个治疗过程。
需要说明的是,在本专利的申请文件中,诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来,而不一定 要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且,术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含,从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素,而且还包括没有明确列出的其他要素,或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下,由语句“包括一个”限定的要素,并不排除在包括该要素的过程、方法、物品或者设备中还存在另外的相同要素。本专利的申请文件中,如果提到根据某要素执行某行为,则是指至少根据该要素执行该行为的意思,其中包括了两种情况:仅根据该要素执行该行为、和根据该要素和其它要素执行该行为。多个、多次、多种等表达包括2个、2次、2种以及2个以上、2次以上、2种以上。
在本说明书提及的所有文献都被认为是整体性地包括在本申请的公开内容中,以便在必要时可以作为修改的依据。此外应理解,以上该仅为本说明书的较佳实施例而已,并非用于限定本说明书的保护范围。凡在本说明书一个或多个实施例的精神和原则之内,所作的任何修改、等同替换、改进等,均应包含在本说明书一个或多个实施例的保护范围之内。
在一些情况下,在权利要求书中记载的动作或步骤可以按照不同于实施例中的顺序来执行并且仍然可以实现期望的结果。另外,在附图中描绘的过程不一定要求示出的特定顺序或者连续顺序才能实现期望的结果。在某些实施方式中,多任务处理和并行处理也是可以的或者可能是有利的。
Claims (10)
- 一种射频热消融***,其特征在于,包括:热消融探头,所述热消融探头包括带电感特性的绝缘加热绕组,该电感特性用于配置检测时的频率工作点,增强检测绕组圈间寄生电容的灵敏度;射频发生器,用于向所述加热绕组输出用于加热的射频功率;圈间寄生电容监测装置,用于在加热过程中监测因管状器官壁接近绝缘加热绕组和/或体液凝固产生的所述绝缘加热绕组圈间寄生电容的变化;控制装置,用于根据所述圈间寄生电容监测装置检测到的圈间寄生电容的变化,控制所述射频发生器向所述加热绕组输出的射频功率大小。
- 如权利要求1所述的射频热消融***,其特征在于,所述圈间寄生电容监测装置通过检测所述加热绕组的矢量电压和电流,监测所述加热绕组圈间寄生电容的变化。
- 如权利要求2所述的射频热消融***,其特征在于,所述控制装置还用于,根据所述圈间寄生电容监测装置检测到的所述加热绕组的矢量电压和电流计算所述加热绕组圈间寄生电容,并提取所述加热绕组圈间寄生电容和绕组电感特性合成后的阻抗相位,如果所述相位进入预设区间,则控制所述射频发射器停止向所述加热绕组输出射频功率。
- 如权利要求3所述的射频热消融***,其特征在于,所述控制装置输出频率连续可调;所述控制装置还用于,在预先设定的工作频率范围,搜索和调整所述射频发生器输出的射频功率的工作频率,使得该工作频率与所述复阻抗的共振频率的差值小于预定门限。
- 如权利要求4所述的射频热消融***,其特征在于,在抵消电路寄生电容后,所述工作频率范围覆盖所述加热绕组复阻抗的相位从90度到-90度的变化范围。
- 如权利要求4所述的射频热消融***,其特征在于,所述加热绕组的圈间间距满足以下条件:使得该加热绕组的电感和预期圈间寄生电容的组合所对应的共振频率在所述工作频率范围内,其中所述预期圈间寄生电容是血管组织与所述热消融探头的距离在预定范围内时所述加热绕组的圈间寄生电容。
- 如权利要求6所述的射频热消融***,其特征在于,还包括存储器,用于存储预先标定的共振频率,作为目标共振频率供使用时所述控制装置读取。
- 一种射频热消融***的控制方法,其特征在于,所述射频热消融***包括:热消融探头,所述热消融探头包括带电感特性的绝缘加热绕组,该电感特性用于配置检测时的频率工作点,增强检测绕组圈间寄生电容的灵敏度;射频发生器,用于向所述绝缘加热绕组输出用于加热的射频功率;所述方法包括:所述射频发生器向所述绝缘加热绕组输出用于加热的射频功率;在加热过程中监测所述因管状器官壁接近绝缘加热绕组和/或体液凝固产生的所述绝缘加热绕组圈间寄生电容的变化;根据检测到的圈间寄生电容的变化,控制所述射频发生器向所述绝缘加热绕组输出的射频功率大小。
- 如权利要求8所述的射频热消融***的控制方法,其特征在于,所述在加热过程中监测所述绝缘加热绕组圈间寄生电容的变化,进一步包括:通过检测所述加热绕组的矢量电压和电流,监测所述加热绕组圈间寄生电容的变化;所述根据所述圈间寄生电容监测装置检测到的圈间寄生电容的变化,控制所述射频发生器向所述加热绕组输出的射频功率大小,进一步包括:根据检测到的所述加热绕组的矢量电压和电流计算所述加热绕组圈间寄生电容,并提取所述加热绕组圈间寄生电容和绕组电感特性合成后的阻抗相位,如果所述相位进入预设区间,则控制所述射频发射器停止向所述加热绕组输出射频功率。
- 如权利要求9所述的射频热消融***的控制方法,其特征在于,所述在加热过程中监测所述绝缘加热绕组复阻抗的变化之后,还包括:在预先设定的工作频率范围,搜索和调整所述射频发生器输出的射频功率的工作频率,使得该工作频率与所述复阻抗的共振频率的差值小于预定门限。
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Also Published As
Publication number | Publication date |
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EP3998032A4 (en) | 2023-08-02 |
EP3998032A1 (en) | 2022-05-18 |
CN111803204A (zh) | 2020-10-23 |
CN111803204B (zh) | 2022-07-01 |
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